Earpiece integrated magnetic shielding for mitigating ingress of magnetic particles

Abstract

This document describes methods and apparatus for reducing a magnetic field emitted by an earpiece assembly from extending substantially outside a device associated with the earpiece assembly. Where the earpiece assembly is susceptible to ingress of magnetically attractable particles into the earpiece assembly such a reduction can prolong an operational life of the earpiece assembly. By insert molding magnetically permeable materials throughout an enclosure that surrounds and supports a permanent magnet of the earpiece assembly, a portion of a magnetic field emanating from the permanent magnet that extends outside the device can be substantially reduced or redirected so that the magnetic field ceases to draw the magnetically attractable particles into the earpiece assembly.

What is claimed is: 
     
       1. A speaker assembly for an electronic device, the speaker assembly comprising:
 a speaker, comprising a magnetic element that emits a magnetic field used to actuate an acoustic membrane that generates audio signals during operation of the speaker assembly; and 
 a speaker enclosure substantially surrounding the speaker assembly and defining an opening that provides an outlet for the audio signals generated by the acoustic membrane, the speaker enclosure comprising magnetically permeable material distributed around the opening in a manner that redirects the magnetic field so that magnetically attractable particles from an external environment are inhibited from being magnetically drawn through the opening. 
 
     
     
       2. The speaker assembly as recited in  claim 1 , wherein the redirection of the magnetic field by the magnetically permeable material reorients a plurality of magnetic field lines of the magnetic field away from a direction normal to an entrance into the opening defined by the speaker enclosure. 
     
     
       3. The speaker assembly as recited in  claim 2 , wherein magnetic forces generated by the magnetic field and exerted upon the magnetically attractable particles are directed away from the opening as a result of the reorienting of the plurality of magnetic field lines. 
     
     
       4. The speaker assembly as recited in  claim 3 , wherein the speaker further comprises:
 an electrically conductive ring across which the acoustic membrane is stretched, the electrically conductive ring being electrically coupled with a power supply; 
 wherein the power supply is configured to supply modulated electrical current to the electrically conductive ring to produce a modulating magnetic field that interacts with the magnetic field emitted by the magnetic element that causes the acoustic membrane to vibrate in accordance with audio information received by the electronic device. 
 
     
     
       5. The speaker assembly as recited in  claim 4 , wherein the electrically conductive ring is flexibly coupled to interior surfaces of the speaker enclosure, the flexible coupling aligning a longitudinal axis of the electrically conductive ring with a pole of the magnetic element. 
     
     
       6. The speaker assembly as recited in  claim 4 , wherein the opening defined by the speaker enclosure exposes at least half of the acoustic membrane. 
     
     
       7. The speaker assembly as recited in  claim 2 , wherein the speaker enclosure further comprises molding material insert molded around the magnetically permeable material. 
     
     
       8. A speaker assembly configured to be affixed to an interior surface of a housing of an electronic device, the speaker assembly comprising:
 a speaker enclosure defining an opening leading towards a position at which an opening in the interior surface of the housing is positioned when the speaker assembly is affixed to the interior surface of the housing, the speaker enclosure comprising magnetically permeable material arranged around the opening defined by the speaker enclosure; 
 a magnet disposed within and substantially surrounded by the speaker enclosure; 
 an electrically conductive ring electrically coupled with a power supply that supplies the electrically conductive ring with modulated current during operation of the speaker assembly; and 
 a diaphragm coupled with and disposed across the electrically conductive ring, 
 wherein the electrically conductive ring and the magnet cooperate to vibrate the electrically conductive ring so that the diaphragm generates an audio signal that is transmitted through the opening defined by the speaker enclosure, and wherein the magnetically permeable material is positioned to redirect portions of magnetic fields emitted by the speaker assembly that extend outside of the electronic device to reduce a rate at which magnetically attractable particles are drawn into the speaker assembly. 
 
     
     
       9. The speaker assembly as recited in  claim 8 , wherein the rate at which the magnetically attractable particles are drawn into the speaker assembly is reduced by reorienting a plurality of magnetic field lines of the portion of the magnetic fields away from a direction normal to an entrance into the opening in the interior surface of the housing. 
     
     
       10. The speaker assembly as recited in  claim 8 , wherein an acoustic mesh is positioned across the opening leading out of the speaker enclosure. 
     
     
       11. The speaker assembly as recited in  claim 8 , wherein the magnetically permeable material of the speaker enclosure is concentrated between the magnet and the interior surface of the housing. 
     
     
       12. The speaker assembly as recited in  claim 8 , wherein the diaphragm is formed from paper. 
     
     
       13. The speaker assembly as recited in  claim 8 , wherein the magnetically permeable material comprises stainless steel. 
     
     
       14. The speaker assembly as recited in  claim 8 , further comprising additional magnetically permeable material formed of mu-metal. 
     
     
       15. The speaker assembly as recited in  claim 8 , further comprising a layer of cosmetic mesh configured to cover the opening in the interior surface defined by the housing. 
     
     
       16. The electronic device as recited in  claim 8 , wherein the speaker enclosure further comprises a magnetic shunt that supports the magnet and forms at least a portion of one side of the speaker enclosure, and wherein the magnetic shunt interlocks with an injection molded portion of the speaker enclosure to position the magnet proximate to the electrically conductive ring. 
     
     
       17. The electronic device as recited in  claim 16 , wherein the magnetic field emitted by the magnet is substantially aligned with the resulting magnetic field emitted by the electrically conductive ring. 
     
     
       18. An electronic device, comprising:
 a device housing defining a speaker opening; and a speaker assembly affixed to an interior facing surface of the device housing that includes the speaker opening, the speaker assembly comprising: a speaker enclosure defining an opening oriented towards the speaker opening in the interior facing surface of the device housing, the speaker enclosure comprising magnetically permeable material distributed around the opening defined by the speaker enclosure, a magnet disposed within and substantially surrounded by the speaker enclosure, and an acoustic membrane stretched over an electrically conductive ring, the electrically conductive ring configured to emit a shifting magnetic field that cooperates with a magnetic field emitted by the magnet to cause the acoustic membrane to generate an audio output that is transmitted through the opening of the speaker enclosure and the speaker opening, and wherein the magnetically permeable material is positioned to redirect a portion of the magnetic field emitted by the magnet from extending outside of the electronic device. 
 
     
     
       19. The electronic device as recited in  claim 18 , wherein a rate at which magnetically attractable particles are drawn into the speaker enclosure by the magnetic field is reduced by reorienting a plurality of magnetic field lines of the magnetic field away from a direction normal to an entrance into the speaker opening.